1. Field of the Invention
This invention relates to an improved tarp enclosure system. More particularly, the invention relates to a retractable tarp enclosure system which may be used for covering substantially any area or object, including beds of trucks, trailers and the like, and which includes tensioning and locking mechanisms and a single piece tarp which make the system more efficacious and convenient to use than conventional systems.
2. Discussion of Background Art
Tarp covering and enclosure systems have long been known for use in a wide variety of applications, including tents, greenhouses and other space enclosures, awnings, swimming pool covers, vehicle load covers, etc. Some of the known systems are more complex than others including systems which are large, systems which are tensioned, systems which are movable, etc.
In larger systems it is often desirable to use a number of tarp sections which are joined together using connectors with retaining grooves or recesses which slidingly receive and retain enlarged edges of the tarp sections. By forming the tarps in sections, it is easier to manipulate the tarp and easier to replace individual sections when they become worn or damaged, for example. Some sectional tarp systems are disclosed in U.S. Pat. Nos. 2,950,727, 3,415,260, 3,469,587, 3,534,511, 3,875,623, and 4,137,687. Also, various components for making a sectional tarp cover have been readily available for decades under the trade name KEDER™, for example.
When a tarp cover system is movable, it will typically include wheeled carriages, skids, and/or other mechanisms which permit the cover system to be moved to various positions, and may include a drive assembly for facilitating the movement from a remote location. Also, a movable tarp cover system may include mechanism(s) for securing or locking the cover system in various positions, such as a fully closed/covering position and a fully retracted/non-covering position, and may also include mechanism(s) for tensioning the tarp cover for improved aerodynamics, appearance and durability.
Applicant has previously proposed several cover systems which may, for example, be used for covering loads on flatbed trucks/trailers as a so-called rolling type tarpaulin system. One such enclosure system shown in U.S. Pat. No. 5,924,759 includes a plurality of U-shaped bows supporting a flexible cover, and rails provided along opposite sides of the truck bed which support ends of the bows through wheeled carriages such that the tarp cover may be easily moved longitudinally along the bed permitting the tarp to be extended over the bed or collapsed in an accordion-like manner. See FIG. 14. Although not disclosed in U.S. Pat. No. 5,924,759, at least one of applicant's previously proposed systems includes locking mechanisms for the two ends of the tarp enclosure which also permit the tarp enclosure to be tensioned at either/both ends. This is desirable for an operator because it permits any portion of the flatbed to be conveniently exposed and covered. The disclosure of U.S. Pat. No. 5,924,759 is incorporated herein by reference.
While the conventional cover systems, including those previous systems proposed by applicant, are generally effective for their intended purposes, the conventional systems remain to be improved upon in various respects.
The Rear Tensioning and Locking Mechanisms
For example, in many truck mounted rolling type tarpaulin systems there is typically provided some type of tensioning mechanism associated with the rear end of the system, whereby when the system is in its fully closed position and the front bow is locked in position, e.g., in engagement with the headboard at the front of the truck trailer, the tarp cover can be stretched taut by moving the rearmost supporting bow rearwardly a few inches. One common tensioning mechanism involves use of a vertical post attached to the rear of the trailer extending upwardly approximately half the height of the rear bow and one or more tensioning straps which are used to pull the rear bow towards the post. The tensioning strap located near the center of the rear bow is usually too high for the operator to reach from ground level and requires the operator to climb on a step or the vehicle's bumper for operation of the tensioning strap. The post may be located inside the covering system so that it is not visible from the outside for aesthetic purposes, but this takes up valuable cargo space. The post may alternatively be located outside of the covering system to avoid reduction in cargo space, but detracts from the system's appearance. In either event, the post is typically removable for loading and unloading cargo, but the post is relatively heavy and creates a burden for the operator.
Another conventional rear tensioning mechanism is one involving a cam which pushes the rear bow rearwardly relative to the floor of the trailer, such as an over-center cam mechanism extended between a vertically intermediate section of the rear bow and the trailer floor, the mechanism being manually manipulated to effect and release a cam action. The cam action functions to both lock the rear bow in position and pushes it rearward to tension the tarp. Such conventional mechanisms are disadvantageous in that they generally concentrate tension to the bottom portion of the tarp system near the guide rail assembly placing an undue load on the support wheels, which is likely to lead to premature failure. The undue load is sustained during transport and with the addition of road vibrations, etc., and the support wheels tend to fail in a relatively short time. A simple cam lock typically can provide only a few inches of tensioning distance which may not be sufficient for the requirements of full size tarp systems for trucks and trailers, e.g., 18 wheeler-type, over the life of the system.
Systems of braces for providing tarp tension have been disclosed in U.S. Pat. Nos. 3,874,721, 4,721,336, 2,486,170, 3,064,667 and 3,326,598. However, all of these brace designs simply maintain the bows along vertical axes and involve tarp covers having little or no tension applied thereto. Correspondingly, none of these designs allow for adjustment of the tilt of the rear bow to achieve balance of any significant tensioning forces between the top and bottom of the end bow.
Applicant has previously proposed a tensioning and locking mechanism for the rear end of a truck mounted cover system which avoids the discussed disadvantages of the conventional post and cam mechanisms. Applicant's previous mechanism, shown on FIG. 11, is a generally triangular brace 100 which attaches to the floor of the truck trailer and has a rearwardly facing hook 102 at its upper end which is manually manipulated to engage a projection fixed to a vertically intermediate portion of the rear bow for thereby locking the rear bow onto the trailer. The brace includes an adjustable screw mechanism 104 operatively associated with the lower end of a diagonal leg 106 of the brace whereby an operator may rotate the screw mechanism with a crank handle 107 or the like for causing the lower end of the diagonal leg 106 to move horizontally toward the rear of the trailer, causing the upper end of the diagonal leg and the hook 102 fixed thereto to move rearwardly, which thereby forces the end bow rearwardly and tensions the tarp cover. The previous system allows for more than several inches of tensioning distance which is generally sufficient for producing high tension on the tarp for full size truck and trailer applications over the life of the tarp system. This previous system can be comfortably operated from ground level and is located inside the tarp system to maintain aerodynamics and aesthetics of the vehicle.
While applicant's previous tensioning and locking mechanism is a significant improvement over the conventional rear locking and/or tensioning mechanisms, it still remains to be improved upon in some respects, e.g., the brace occupies some space within the cover system that may otherwise be used to store cargo, which is particularly limiting when hauling high volume cargo such as lumber, building supplies, bins, etc. where every square inch of floor space is needed, and the brace must typically be removed when loading/unloading the trailer to avoid interference with the cargo being moved.
The Front Tensioning and Locking Mechanisms
As another example, some conventional mechanisms for tensioning and locking the front end of truck mounted rolling tarp systems to the front end of the truck trailer, e.g., to a headboard permanently fixed at the front end of the trailer, typically use mechanisms which are located externally to the cover system and the headboard. These are disadvantageous in that the mechanisms are exposed to the elements at all times and cause additional wind resistance when the truck is traveling. Other conventional mechanisms are provided within the cover system and/or the headboard, but perform only a locking function, e.g., connecting the front bow to the headboard. These are disadvantageous in that tensioning and de-tensioning of a cover system can only be preformed at the rear of the truck trailer. Thus, for example, if an operator desires to expose a portion of the trailer bed near the front of the trailer, the operator must first release cover tension at the rear of the trailer and unlock the front lock mechanism before he/she is able to move the front portion of the cover system to expose the front portion of the trailer.
Applicant has previously proposed a ratcheting-type tensioning and locking mechanism for the front end of a truck mounted cover system which avoids the discussed disadvantages of the conventional mechanisms. Applicant's previous mechanism, shown in FIGS. 12A, 12B, functions to simultaneously lock the front bow to the headboard and to tension the cover system by pulling the front bow forwardly relative to the rest of the system. The previous system includes, on each front corner of the vehicle, a ratchet mechanism 110 including a vertical rod (not shown) rotatably supported inside a corner of the headboard 112, an elongate pull bar 114 connected to vertical rod of the ratchet mechanism via one or more flexible straps 116, and one or more retaining hooks (not shown) connected to the front bow (not shown) which receive and hold the pull bar. For connecting the front bow to the headboard and simultaneously tensioning the tarp cover, an operator places the pull bar in the hook(s) and then operates the ratchet mechanism with an appropriate tool 118 such that the flexible strap(s) are wound around the vertical rod, thereby drawing the front bow into tight engagement with the headboard and tensioning the tarp cover. Such previous mechanism is advantageous because (among other reasons) it performs locking and tension functions, it is entirely disposed within the headboard and cover system except for a ratchet gear extending beneath a lower corner of the headboard, and is capable of applying a large amount of tension to the tarp cover.
While applicant's previous locking and tensioning mechanism for the front of the cover system is a significant improvement over the conventional front locking and/or tensioning mechanisms, it still remains to be improved upon in terms of ease of use—manipulation by an operator. Particularly, with the previous mechanism, the retaining hook(s) are connected to inwardly facing surface(s) of the front bow, extending and opening towards the rear of the system, such that the operator would have to reach around to the inside of the front bow for attachment and removal of the pull bar relative to the hook(s) as indicated in FIG. 12B. Under these conditions, the operator is working somewhat blindly and relies on his/her sense of touch and familiarity with the location of the hook(s) for placing the pull bar in and removing it from the hook(s). For example, a typical process for disconnecting the pull bar from the front bow hooks involves the operator grabbing the pull bar at an inner face of the front bow, lifting the bar a couple inches, and then moving the bar rearwardly a couple inches to free the bar from the hook(s). These steps are reversed when fitting the pull bar into the retaining hooks.
The Tarp Cover
In truck or trailer mounted cover systems, there are two conventional methods—mechanisms for connecting the tarp cover to the bows supporting same depending on whether the tarp is a single large piece or a plurality of sections which are connected together via the bows or other appropriate connectors. Examples of the conventional methods are shown in FIGS. 13A-13C. In the single piece tarp system of FIG. 13A, the single piece tarp 120 is connected to a supporting bow 122 using smaller pieces of tarp material 124 which are sewn or otherwise fastened to the inside face of the tarp so as to form pockets through which the bow is extended. The pockets may be quite small, e.g., a few inches in depth, or any size up to the continuous full width of the tarp. Conventional single piece tarp systems are disadvantageous for at least three reasons. First, the single piece tarp may be very large, e.g., a full length and height rolling tarp system for a 45 foot long trailer may be 45 long and 25 feet wide, and require several persons to manipulate same for installation and removal. Second, it is difficult to repair or replace any portion of the tarp, e.g., even if only a small portion of the tarp has been damaged. Third, it is difficult to sufficiently hold a single piece tarp tight against all of the bows in a large covering system, and if a rolling type tarp system on a large trailer allows movement between the tarp and bows it may reduce the longevity of the tarp material and otherwise does not have a favorable aesthetic appearance.
In the multiple piece tarp system of FIG. 13B, the individual tarp segments 126 typically have enlarged edges 126a, e.g., with a piece of rope or the like sewn within the edge that has been folded over the rope, and the enlarged edges may then be slidably inserted into openings or grooves formed in opposite sides of supporting bows/connectors 128. The cross sectional shape of the connector in FIG. 13B is very common and conventional. The multiple piece tarp system of FIG. 13C is a system previously proposed by applicant. In this system, the connector bows are different from the connector of FIG. 13B in that the bow includes a hollow tubular portion with a single groove/recess formed on one face of the tube, and the groove has two lobes which receive the enlarged edges of a pair of tarp segments. With this construction the bow is desirably hidden from view on the outside of the system because the bow is covered by the tarp segments.
Numerous segmented systems have been conventionally available for many decades, including connectors formed from a single molded or extruded piece, connectors formed in multiple pieces which are joined together, etc., but the connectors all function similarly to slidingly receive and retain the enlarged edges of the cover sections such that each cover section may be removed from the system, e.g., for repair or replacement, without removing any other segment. Some segmented tarp system components have long been available as off-the-shelf items sold under the trade name KEDER™, for example, which may be used to create a segmented tarp cover for any given application.
The conventional segmented cover systems overcome the disadvantages of the single piece tarp systems, but introduce some other potential disadvantages. One potential disadvantage is that water may leak through the connection between two adjacent tarp segments, especially with connectors formed as hollow members and where a bow/connector is formed from several parts which are bolted or otherwise connected together as is commonly done at transitions in bows at such right angle corners. For example, applicant has previously proposed a multiple piece bow/connector for a rolling tarp system including upper corner sections which are constructed quite different from the other sections which are simple straight extrusions because the corners require greater strength. Another potential disadvantage is that water may condense on the bows when the cover system moves through different environments with different temperatures such as when moving into or out of a climate controlled building. The tarpaulin material is relatively thin and can change temperature much faster than the bow material, typically extruded aluminum, which is large and thick in comparison to the tarpaulin material. Thus, for example, the condensation from the atmosphere within the cover system may condense as droplets on the bow surfaces and drop onto cargo covered by the system. Still another potential disadvantage is that the extruded aluminum bows are typically non-anodized, such that they can be extruded into desired shapes very easily and inexpensively. However, the non-anodized aluminum forms a natural oxidation on its outer surface which may leave undesirable black marks on any object that the bows contact. For some types of cargo, it would be undesirable to have such black marks formed thereon. Yet another disadvantage of segmented systems is that the segments tend to move along the bow/connector over time, especially when the cover system is mounted on truck trailer or other moving support, such that adjacent segments may become somewhat misaligned relative to each other. If the tarp has graphics, e.g., a company's name or logo, printed across two or more segments the graphics may have an undesirable jagged appearance due to the misalignment.
Thus, a need still exists in the art for an improved tarp enclosure system which addresses and overcomes the above-discussed disadvantages.